Cement is used to prepare concrete and concrete is used in a wide variety of applications, including, but not limited to, roads, parking lots, bridges, walkways, support structures such as walls, foundations, and beams. Concrete can often be exposed to the outdoors and in particular to water. Additionally, in many geographic regions, concrete can be exposed to significant temperature changes from winter to summer, in addition to rain, snow, and significant changes in humidity. Further, concrete is often subject to significant wear and stress. For example, concrete may be used as part of a structural support for a building where it supports significant weight and must be capable of withstanding storms and high winds. Over the last 50 years, cements and concretes have seen a number of minor improvements; however, the general strength and durability has largely remained the same, particularly of the cement.
Further, much attention has recently been directed to chloride ion penetration of concrete compositions due to the corrosion of reinforced steel in reinforced concrete. Corrosion related damage to many structures has been a significant problem, which is discussed in “Rapid Chloride Permeability Testing” by Prakash Joshi and Cesar Chan, Publication #CO2L037 2002, Hanley-Wood, LLC. Chloride ions can penetrate concrete in various ways. For example, Joshi and Chan report that chloride ions penetrate crack-free concrete by capillary absorption, hydrostatic pressure, diffusion, and evaporative transport. The end-result is that the rebar ultimately corrodes resulting in structural deficiencies and necessary repairs. To address this problem, cement compositions have been prepared with the inclusion of corrosion inhibitors. However, including corrosion inhibitors does not ultimately prevent corrosion from occurring, it merely delays corrosion. And the addition of corrosion inhibitors can be expensive in cement formulation.
Accordingly, it is an objective to provide cement compositions used in concrete such that the concrete has improved physical properties such as reduced permeability and increased compressive and flexural strength.
Another object of the invention is to provide cement compositions used in concrete such that the concrete has improved chloride ion penetrability.
Still another object of the invention is to provide a cost savings by reducing the amount of cementitious materials necessary for preparation of concrete while obtaining certain physical properties.
Other objects, advantages and features of the present invention will become apparent from the following specification.